Evaluation of a 4.5 kW Commercial Hall Thruster System for NASA Science Missions

The readiness of commercial Hall thruster technology is evaluated for near-term use on competitively-award, cost-capped science missions like the NASA Discovery program. Scientists on these programs continue to place higher demands on mission performance that must trade against the cost and performance of propulsion system options. Solar electric propulsion (SEP) systems can provide enabling or enhancing capabilities to several missions, but the widespread and routine use of SEP will only be realized through aggressive cost and schedule risk reduction efforts. Significant cost and schedule risk reductions can potentially be realized with systems based on commercial Hall thruster technology. The abundance of commercial suppliers in the United States and abroad provides a sustainable base from which Hall thruster systems can be cost-effectively obtained through procurements from existing product lines. A Hall thruster propulsion system standard architecture for NASA science missions is proposed. The BPT-4000 from Aerojet is identified as a candidate for near-term use. Differences in qualification requirements between commercial and science missions are identified and a plan is presented for a low-cost, low-risk delta qualification effort. Mission analysis for Discovery-class reference missions are discussed comparing the relative cost and performance benefits of a BPT-4000 based system to an NSTAR ion thruster based system. The BPT-4000 system seems best suited to destinations located relatively close to the sun, inside approximately 2 AU. On a reference near Earth asteroid sample return mission, the BPT-4000 offers mass performance competitive with or superior to NSTAR at much lower cost. Additionally, it is found that a low-cost, mid-power commercial Hall thruster system may be a viable alternative to aerobraking for some missions. Suggestions for the near- and far-term implementation of commercial Hall thrusters on NASA science missions are discussed.